What should it cost for a tune up? on 2002 Infiniti I35

I took this car in for a tune up and have been told it will cost $800 for the tune up and $191 to replace a valve cover gasket. I know the intake manifold has to come off to do this but it seems high to me.

Asked by for the 2002 Infiniti I35
My labor guide says 1 hour to replace the left valve cover gasket, 3.5 to do the right. They must be quoting for more than a tune up. Valves hydraulically adjust themselves no adjustment necessary, probably quoting platinum spark plugs but tune up sounds high.
In addition to the tune up i was to told that the spark plug boots should be replaced as well as the fuel filter. The valve cover gasket was leaking in the area of the center plug. Not sure which side.
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tune up at our shop about 500-600. which valve cover gasket and why??